Apparatus for heat-treating gear teeth



Oct. 3, 1950 F. s. DENNEEN ETAL APPARATUS FOR HEAT-TREATING GEAR TEETH 2 Sheets-Sheet 1 Filed Aug. 10, 1944 Oct. 3, 1950 F. s. DENNEEN ETAL 2,

APPARATUS FOR HEAT-TREATING GEAR TEETH Filed Aug. 10, .1944 2 Sheets-Sheet 2 Fatented et. 3;, 19 50 APPARATUS FOR HEAT-TREATING GEAR TEETH Francis S. Denneen, Cleveland, and William C. j Dunn, Shaker Heights, Ohio, assignors to The Ohio Crankshaft Company, Cleveland, Ohio, a

corporation of Ohio Application August 10, 1944, Serial No. 548,888

The present application as a continuation in part of our co-pending application Serial Number 389,847, filed April 23, 1941, now Patent Number 2,356,150, issued on August 22, .1944, is

1 Claim. (crass-4) approximately 180 degrees when the gear and cooling bath approach each other, thereby bringing the tooth just treated into the cooling bath and the opposite tooth into position to be moved directed to apparatus and. method for heat treatinto operative relation with the induction heater ing gear teeth. The apparatus shown in this and quenching means. 7 application comprises an inductor closely related With these and other objects in view, this into that shown in the former application and the vention then consists of the method herein quenching mechanism employed is similar. How- I explained and of apparatus for accomplishing ever, other means is employed for accomplishing this method. The annexed drawings and folrelative movement of inductor and gear to bring lowing description set forth in detail one form the inductor into heating relation with succesof the apparatus embodying-the invention, which sively heated teeth of the gear, and supplemental apparatus may be constructed in many ways controlled cooling is rovided. within the scope of the appended claims.

Heretofore, it has been customary to move the In the said drawings: inductor toward and away from the parts of large Fig. 1 is a front elevation showing the preferred gears and similar articles being heat treated as form of our apparatus. 4

in the above co-pending application in which Fig. 2 is a side elevation as indicated at 2'2 of the inductor is hinged to move out of proximity Fig. 1. with the surface zones of the teeth and to move Fig. 3 is asection at 3-3 of Pi .1. past the quenching members employed, the Fig. 4 is a section substantia y at 44 of Fig. 1. quenching being completed while the inductor is Fig. 5 is an enlarged section at 5-5 of Fig. 1. in heating position. Such heating and quench- Referring now to the drawings anfapparatus ing can be applied successfull on only som types comprises the base I I having an upper part servof material and usually a subsequent and fur ing asa cylinder in which a piston l2 serves as ther heat treatment is required to reduce internal means for elevating a gear I3, theteeth of which stresses and to avoid surface cracks resulting are to be hardened. The gear forms no part from such stresses. of the present invention but, of course, should The chief object of this invention has been to preferably be formed of a material having quench provide means for hardening in rapid succession 0 hardening characteristics, which characteristics surface zones of the teeth of a large-gear. A alsogenerally include tempering characteristics further object has been to provide means for should the 'quench hardened surface be held at cooling after hardening such surface zones. A an elevated temperature for any lengthof time. further object has been to provide power means Piston rod H at its upper end carries the gear for moving the gear and means to hold the gear 3:, support I5, this support being provided with a accurately in position after movement. An addistub shaft l6 of such size as to enter the bore of tional object has been to provide a compact he hub of the gear and turn with it. Valve 18, apparatus easily operated by unskilled labor. which may be foot or hand operated, serves as Other pbjects will become apparent from the means for supplying pressure fluid to raise the following description. 4;) piston 12. To control the movement of the gear One of such objects is the provision of a new I3 and to relieve the piston rod 14 of bending and improved apparatus for heat treating gear loads, a guide barlll is provided which passes teeth comprising the combination of a mounting through and guides the gear support l5. The unit for the gear being treated, including a, spinbar 20 is secured to the side of the cylindrical die, and a tooth-treating unit including an in- H part of base l duction heater and quenching means associated At the upper end of bar 20 is a, platform 2| therewith, the heater and associated quenching adapted to carry the heating mechanism which means being positioned above the spindle for comprises thetransformer 22 and the inductor 23 heating and quenching a tooth of the gear on with its associated quenching chamber 24 atthe spindle, the tooth-treating unit further intached. to a part of this platform. Additional eluding a cooling bath positioned below the spinirame members such as bar 25 serve to provide dle opposite the heater and quenching means, the rigidity to the structure supporting the platform combination also including means for effecting 2|. A tank is attached to a side of base H relative reciprocable movement between the and a moving platform or loading table 3| is mounting unit and the tooth-treating unit to supported on the tank or on some other conbring the gear info successive engagement, with venient part of the apparatus. The tank is prothe induction heater and quenching means at the vided with blocks or lugs 32 in itsbottom to supupper position and the cooling bath at the lower port and locate the gear while insertin in and position. The combination also includes means, removing shaft l8 from the bore of the gear hub. including a one-way switch, for turning the gear on To rotate or index the gear to each new position in heating successive teeth. a rack 85 is provided which is supported at its lower end on the base II or tank 30 and which meshes with pinion It. This pinion is carried on shaft 86 b means of a free wheel or roller clutch mechanism arranged to rotate the shaft only while the gear descends. An indexing lock 38 having an a'ctuating'spring serves as means for holding the gear in its rotated position.

Operation The apparatus above described is normally operated as follows? The gear l3 whose teeth are to have their wearing surfaces zone hardened is placed on table 31 by means of a suitable hoist, the table being adiusted to bring the gear into such position as to be easily rolled or slid into position on the lugs 32 in the tank, these lugs being so located as to bring the gear into a central position with the center Of the bore of its hub lying opposite the line of travel f the shaft l6. Shaft I6 is brought to correct elevation by operating valve 10 and the gear is then slid or otherwise moved along lugs 32 to cause the shaft to enter the bore of the gear, where it is secured by means of the nut on the end of the shaft.

By fluid pressure from valve l8 applied under piston 12 the wheel support I is raised elevating the gear to bring one of the gear teeth into the space between the sides of inductor 23, the indexing lock 38 having been adjusted to so engage another tooth as to bring the tooth to be hardened into correctly spaced relation with the two sides of the inductor. The adjustable stop screw 40 limits the movement of the gear to prevent the inductor members from entering too deeply into the tooth spaces. With the tooth in place in the inductor, switch II is closed and current of relatively high frequency is applied to the inductor to rapidly heat the surface zones of the tooth, after which quenching fluid is applied by valve 43 which admits such fluid at a relatively high pressure to quenching chamber 24 from where it is projected onto and along the sides of the tooth by suitably directed orifices leading from this quenching chamber. Quenching is usually interrupted while the temperature of the surface zones is still relatively high. The

temperature at which the tooth is heated will, of '0 course, depend upon its metallurgical characteristics and the final metallurgical characteristics desired. For most steels this temperature is in the neighborhood of 1550 F. This temperature may be secured by adjusting either the rate of power input to the inductor or the length of time of power input, or both. Similarly the amount and degree of quench will be determined by the hardness which it is desired to obtain after the final tempering operation. state the exact amount of quench necessary as it will vary radically between different grades and kinds of steel and on the character of the final hardened surface. Pressure is at once released from beneath piston I: which permits the gear to descend. Rack by its engagement with pinion 36 and the over running clutch in the pinion cause the gear to turn approximately 180 in its descent bringing the partly quenched tooth into liquid provided in tank 30 which controls the removal of the remainder of the heat, a part of the heat having been removed by radiation and conduction during the descent. The rate of descent is controlled by valve l8 to regulate the time during which the radiation and conduction It is impossible to N b r take place and thus the amount of'heat being removed during the descent. The temperature of the liquid iii the tank 30 is so regulated as to leave the gear tooth in a properly hardened condition.- Adjustable stop screw 45 limits the depth to which the gear teeth can enter the liquid in tank 30.

By means of the rack and pinion and the stop screw adjustment the descent of the gear after hardening the second tooth causes it to rotate one tooth space less than to bring the inductor into heating relation with a tooth adjacent to the tooth first hardened. Thesesteps are repeated until all teeth have been hardened.

Other forms may be employed embodying the featureszo'f our invention instead of the one herein explained, change being made as regards the meansand the steps herein disclosed, provided the elements stated by the following claim or equivalent of such stated elements be employed, whether produced by our preferred method or by others embodying steps equivalent to those stated in the following claim.

We therefore particularly point out and distinctly claim as our invention:

In an apparatus for heat treating gear teeth, the combination of a mounting unit for the gear being treated, including a spindle, a tooth treating unit, including an induction heater and quenching means associated therewith, said heater and associated quenching means being positioned above said spindle, for heating and quenching a tooth of the gear on the spinde, said tooth treating unit further including a cooling bath positioned below said spindle opposite said heater and quenching means, means for effecting relative reciprocal movement between said mounting unit for the gear and said tooth treating unit, for bringing the gear being treated into successive engagement with the induction heater and quenching means at the upper position and the cooling bath at the lower position, and means, including a one-way clutch, for turning said gear approximately 180 when said gear and said cooling bath approach each other, thereby bringing the tooth just treated into the cooling bath and the tooth opposite the tooth just treated, into operative relation with said induction heater and quenching means.

FRANCIS s. DENNEEN. WILLIAM c. DUNN.

REFERENCES CITED The following references are of record in the file of this patent:

UNI'IED STATES PATENTS Name Date 974,099 Sundborg Oct. 25, 1910 1,711,633 Dornseif May 7, 1920 1,768,159 Shorter et a1. June 24, 1930 2,145,864 Denneen et a1. Feb. 7, 1939 2,202,758 Denneen et al May 28, 1940 2,294,063 Wolf Aug. 25. 1942 2,356,150 Denneen et al. Aug. 22, 1944 2,359,273 Somes Sept. 26, 1944 FOREIGN PATENTS Number Country Date 225,333 Great Britain Dec. 4, 1924 416,928 Great Britain Sept. 17, 1934 448,241 Great Britain Mar. 11, 1935 630,844 Germany June 6. 1936 

